(1) Field of the Invention
This invention relates to a process for preparing a printed-circuit board, and more particularly to a process for preparing a printed-circuit board having excellent developing properties by use of a positive photo-sensitive electrodeposition coating composition.
(2) Description of the Prior Art
In recent years, printed-circuit boards have widely been produced by use of a photo-sensitive electrodeposition coating composition. Recently, it has been demanded to provide a process for preparing a printed-circuit board having a fine pattern and having through-holes with a hole diameter of 0.4 mm or less at high efficiency and reliability. In order to provide the above process, many processes for preparing a printed-circuit board, for example, by use of a positive photo-sensitive electrodeposition coating composition have been proposed (see, for example, Japanese Patent Application Laid-Open Nos. 207139/85, 206293/86, 6070/88, etc.).
The industrial advantages of preparing the printed-circuit board by use of the positive photo-sensitive electrodeposition coating composition (hereinafter may be referred to as the positive electrodeposition coating composition) are in that use of the electrodeposition coating composition makes it possible to form a resist film in the interior of through-holes and also makes it possible to easily prepare a printed-circuit board having such small conductive holes, i.e. through-holes as to be difficult for being exposed to light, because there is no need of curing a resist film with an actinic ray and making it insoluble in a developing solution as in the case of the negative resist film.
In spite of the above advantages, the positive electrodeposition coating composition has, on the other hand, such disadvantages that developing properties at the time of developing the resist film are easily affected by the developing conditions such as humidity, temperature, time and the like due to small differences in solubility to an alkaline developing solution between an exposed area and an unexposed area, resulting in making it impossible to obtain a printed-circuit board having high resolution with good reproductivity.